U.S. patent application number 12/361136 was filed with the patent office on 2010-07-29 for apparatus for isolating multiple circuit boards from vibration.
This patent application is currently assigned to Honeywell International Inc.. Invention is credited to Lori Armon, Larren Elton Boyd, Daniel Goldman.
Application Number | 20100188825 12/361136 |
Document ID | / |
Family ID | 42270028 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100188825 |
Kind Code |
A1 |
Armon; Lori ; et
al. |
July 29, 2010 |
APPARATUS FOR ISOLATING MULTIPLE CIRCUIT BOARDS FROM VIBRATION
Abstract
An apparatus for isolating an electronic device from vibration
is provided. The apparatus includes a rigid frame and a circuit
board assembly comprising a plurality of circuit boards. A first
isolator is located on a first side of the circuit board assembly
between the circuit board assembly and the rigid frame, wherein the
first isolator is held in place by equal and opposite forces from
the rigid frame and the circuit board. A second isolator is located
on a second side of the circuit board assembly between the circuit
board and the rigid frame. The second isolator is substantially
opposite of the first isolator in relation to the circuit board
assembly, wherein the second isolator is held in place by equal and
opposite forces from the rigid frame and the circuit board. A third
isolator is located on a third side of the circuit board assembly
between the circuit board assembly and the rigid frame, wherein the
third isolator is held in place by equal and opposite forces from
the rigid frame and the circuit board. A fourth isolator is located
on a fourth side of the circuit board assembly between the circuit
board assembly and the rigid frame. The fourth isolator is
substantially opposite of the third isolator in relation to the
circuit board assembly, wherein the fourth isolator is held in
place by equal and opposite forces from the rigid frame and the
circuit board.
Inventors: |
Armon; Lori; (Minneapolis,
MN) ; Goldman; Daniel; (Minneapolis, MN) ;
Boyd; Larren Elton; (Golden Valley, MN) |
Correspondence
Address: |
HONEYWELL/FOGG;Patent Services
101 Columbia Road, P.O Box 2245
Morristown
NJ
07962-2245
US
|
Assignee: |
Honeywell International
Inc.
Morristown
NJ
|
Family ID: |
42270028 |
Appl. No.: |
12/361136 |
Filed: |
January 28, 2009 |
Current U.S.
Class: |
361/748 |
Current CPC
Class: |
H05K 7/1434
20130101 |
Class at
Publication: |
361/748 |
International
Class: |
H05K 7/00 20060101
H05K007/00 |
Claims
1. An electronic device comprising: a rigid frame; a circuit board
assembly comprising a plurality of circuit boards; a first isolator
on a first side of the circuit board assembly between the circuit
board assembly and the rigid frame, wherein the first isolator is
held in place by equal and opposite forces from the rigid frame and
the circuit board; a second isolator on a second side of the
circuit board assembly between the circuit board and the rigid
frame, wherein the second isolator is substantially opposite of the
first isolator in relation to the circuit board assembly, and
wherein the second isolator is held in place by equal and opposite
forces from the rigid frame and the circuit board; a third isolator
on a third side of the circuit board assembly between the circuit
board assembly and the rigid frame, wherein the third isolator is
held in place by equal and opposite forces from the rigid frame and
the circuit board; and a fourth isolator on a fourth side of the
circuit board assembly between the circuit board assembly and the
rigid frame, wherein the fourth isolator is substantially opposite
of the third isolator in relation to the circuit board assembly,
and wherein the fourth isolator is held in place by equal and
opposite forces from the rigid frame and the circuit board.
2. The apparatus of claim 1, wherein the first, second, third, and
fourth isolators consist essentially of an elastomer material.
3. The apparatus of claim 1, wherein the isolators are under
compression.
4. The apparatus of claim 1, wherein the isolators are positioned
on edges of the circuit boards on the circuit board assembly.
5. The apparatus of claim 1, wherein the isolators are under
tension.
6. The apparatus of claim 1, wherein the frame further comprises a
plurality of features, wherein the first isolator is configured to
contact the plurality of features.
7. The apparatus of claim 1, wherein a first axis defined by an
imaginary line across the circuit board assembly from the first
isolator to the second isolator, and a second axis is defined by an
imaginary line across the circuit board assembly from the third
isolator to the fourth isolator; wherein the first, second, third,
and fourth isolators are positioned such that the first axis and
the second axis are substantially perpendicular.
8. The apparatus of claim 1, wherein the frame completely surrounds
the circuit board assembly.
9. An electronic device comprising: a frame; a circuit board
assembly within the frame, the circuit board assembly comprising a
plurality of circuit boards; an elastomer material between the
circuit board assembly and the frame, wherein the elastomer
material is held in place by equal and opposite forces.
10. The apparatus of claim 9, wherein the elastomer material is in
compression between the circuit board assembly and the frame.
11. The apparatus of claim 10, wherein the elastomer material
comprises a first isolator on a first side of the circuit board
assembly, a second isolator on a second side of the circuit board
assembly, a third isolator on a third side of the circuit board
assembly, and a fourth isolator on a fourth side of the circuit
board assembly.
12. The apparatus of claim 11, wherein a first axis defined by an
imaginary line across the circuit board assembly from the first
isolator to the second isolator, and a second axis is defined by an
imaginary line across the circuit board assembly from the third
isolator to the fourth isolator; wherein the first, second, third,
and fourth isolators are positioned such that the first axis and
the second axis are substantially perpendicular.
13. The apparatus of claim 10, wherein the frame further comprises
a plurality of features, wherein the first isolator is configured
to contact the plurality of features.
14. The apparatus of claim 9, wherein the elastomer material is
under tension between the circuit board assembly and the frame.
15. The apparatus of claim 9, wherein the elastomer material in
under tension between opposing sides of the frame, and wherein the
circuit board assembly is held within an aperture of the elastomer
material.
16. An isolation system comprising: a circuit board assembly
comprising: a plurality of circuit boards, wherein the circuit
boards are oriented to align in parallel; and a
micro-electrical-mechanical system (MEMS) device; a plurality of
isolators composed of an elastomer material, wherein the plurality
of isolators are located between the circuit board assembly and a
rigid structure; wherein the plurality of isolators are held in
place between the plurality of circuit board assembly and the rigid
structure by equal and opposite forces.
17. The isolation system of claim 16, wherein the plurality of
isolators hold the circuit board assembly in place relative to the
rigid structure.
18. The isolation system of claim 16, wherein the plurality of
isolators are configured to absorb vibration from the rigid
structure.
19. The isolation system of claim 16, wherein the isolators are
under compression from forces of the circuit board assembly and the
rigid structure.
20. The isolation system of claim 16, wherein the isolators are
under tension from forces of the circuit board assembly and the
rigid structure.
Description
BACKGROUND
[0001] Isolation of components from environmental vibration is
important for devices that are sensitive to the vibration
frequencies. For example, to obtain precise measurements, it is
helpful to isolate the measurement devices from the source of the
vibrations. Additionally, some sensitive devices with mechanical
components may fail if vibration frequencies cause the mechanical
components to resonate uncontrollably.
[0002] Conventional vibration isolation devices attach between a
component to be isolated ("isolated component") and some other
structure ("base structure") to which the isolated component is to
be coupled. These isolation devices dampen harmful or unwanted
vibration frequencies propagating through the base structure before
the vibration is coupled to the isolated component. For example, in
some applications metal rings or other rigid structures that
connect the isolated component to the frame are molded with a soft
material thereon to absorb vibrations traveling along the rigid
components. The rigid components of these isolation devices are
typically mounted to the isolation component and to the base
structure by screws or bolts.
[0003] As industry continues to demand smaller overall package
sizes for devices, isolation devices must become smaller as well.
As devices become smaller, however, mounting locations for the
isolation device on the isolated component become limited.
Additionally, as devices become smaller, the mass of the isolated
component may be reduced. This causes changes in the natural
vibration frequency of the device and may be difficult to isolate
with conventional isolators.
SUMMARY
[0004] In one embodiment, an apparatus for isolating an electronic
device from vibration is provided. The apparatus includes a rigid
frame and a circuit board assembly comprising a plurality of
circuit boards. A first isolator is located on a first side of the
circuit board assembly between the circuit board assembly and the
rigid frame, wherein the first isolator is held in place by equal
and opposite forces from the rigid frame and the circuit board. A
second isolator is located on a second side of the circuit board
assembly between the circuit board and the rigid frame. The second
isolator is substantially opposite of the first isolator in
relation to the circuit board assembly, wherein the second isolator
is held in place by equal and opposite forces from the rigid frame
and the circuit board. A third isolator is located on a third side
of the circuit board assembly between the circuit board assembly
and the rigid frame, wherein the third isolator is held in place by
equal and opposite forces from the rigid frame and the circuit
board. A fourth isolator is located on a fourth side of the circuit
board assembly between the circuit board assembly and the rigid
frame. The fourth isolator is substantially opposite of the third
isolator in relation to the circuit board assembly, wherein the
fourth isolator is held in place by equal and opposite forces from
the rigid frame and the circuit board.
DRAWINGS
[0005] Understanding that the drawings depict only exemplary
embodiments of the present invention and are not therefore to be
considered limiting in scope, the exemplary embodiments will be
described with additional specificity and detail through the use of
the accompanying drawings, in which:
[0006] FIG. 1 is an exploded view of one embodiment of a electronic
device including means for isolating electronic components;
[0007] FIG. 2 is a cross-sectional perspective view of the
electronic device of FIG. 1;
[0008] FIG. 3A is a cross-sectional top view of the electronic
device of FIG. 1;
[0009] FIG. 3B is a close-up view of the electronic device of FIG.
3A;
[0010] FIG. 4A is a cross-sectional side view of the electronic
device of FIG. 1;
[0011] FIG. 4B is a cross-sectional perspective view of the
electronic device of FIG. 1;
[0012] FIG. 5 is an exploded view of another embodiment of an
electronic device including means for isolating electronic
components;
[0013] FIG. 6 is a side cross-sectional view of the electronic
device of FIG. 5; and
[0014] FIG. 7 is a cross-section view of the electronic device of
FIG. 5.
[0015] In accordance with common practice, the various described
features are not drawn to scale but are drawn to emphasize specific
features relevant to the exemplary embodiments of the present
invention.
DETAILED DESCRIPTION
[0016] The present disclosure is directed towards an apparatus for
isolating electronic components from vibration. The apparatus
comprises a rigid outer frame housing a circuit board assembly. A
plurality of isolators are located between the circuit board
assembly and the frame to isolate the circuit board assembly from
vibration in the frame and surrounding environment. The isolators
are composed of an elastomer and are located on opposite sides of
the circuit board assembly. The isolators are held between the
circuit board assembly and the frame by equal and opposite forces
on the isolators by the frame and circuit board assembly.
[0017] FIG. 1 illustrates an exploded view of one embodiment of an
electronic device 100 including a means of isolating electronic
components from vibration. Electronic device 100 comprises a
circuit board assembly 102, a plurality of isolators 104, and a
frame 106. For explanation purposes, isolators 104 are labeled
individually as isolator 104-1, 104-2, 104-3, and 104-4, and are
referred to generally as "isolators 104".
[0018] Electronic device 100 isolates circuit board assembly 102
from external environmental vibration by dampening external
vibration with isolators 104. Circuit board assembly 102 comprises
a plurality of circuit boards 108, each circuit board 108 having
four edges 112 and two faces 114. Each circuit board 108 comprises
a plurality of electronic and/or mechanical components. For
example, in one embodiment, circuit board assembly 102 comprises a
gyroscope and associated electronics to obtain measurements from
the gyroscope. Electronic device 100, therefore, comprises a
gyroscope on circuit board assembly 102 mounted in frame 106.
Electronic device 100 can be mounted in a desired location for
taking measurements with the gyroscope by mounting frame 106 to
another structure in the desired location. In one embodiment, the
gyroscope is a micro-electro-mechanical system (MEMS) device and
electronic device 100 is approximately 3.6 cm in diameter.
[0019] In this embodiment, frame 106 comprises a body 110 and a
cover 111 and frame 106 is a hollow cylinder with a top and a
bottom which houses circuit board assembly 102. Thus, in this
embodiment, frame 106 surrounds circuit board assembly 102 in all
three dimensions. Frame 106 is composed of a rigid material
sufficient to support circuit board assembly 102 and isolators 104.
Frame 106 also enables rigid connection between frame 106 and
another structure (not shown). In one embodiment, frame 106 is
composed of aluminum, however; in other embodiments, frame 106 is
composed of other rigid materials such as steel or plastic.
[0020] Although as shown in FIG. 1, frame 106 surrounds circuit
board assembly 102 in three dimensions, in other embodiments, frame
106 is a ring, square, or other similar structure that encircles
circuit board assembly 102 along two axes and is open along a third
axis. Here, frame 106 still supports circuit board assembly 102 at
the locations of isolators 104. Furthermore, in yet another
embodiment, frame 106 substantially surrounds circuit board
assembly 102 in three dimensions, except for an aperture in frame
106 for connection of an electronic cable or the like to circuit
board assembly 106. Although in this embodiment, frame 106 is
cylindrical in shape, in other embodiments other shapes are used
including cube, rectilinear, and other simple or complex
shapes.
[0021] FIG. 2 illustrates a cross-sectional perspective view of one
embodiment of electronic device 100 with circuit board assembly 102
installed in frame 106. Each of the plurality of circuit boards 108
is positioned in parallel such that edges 112 of circuit boards 108
are generally flush with one another. Circuit board assembly 102
comprises two circuit boards 108 that are coupled together with an
interconnect mechanism 201. In an alternative embodiment, circuit
boards 108 are coupled together with flexible cabling. Although the
embodiment illustrated herein comprises two circuit boards 108, in
other embodiments, circuit board assembly 102 comprises more than
two circuit boards 108. Additionally, although circuit boards 108
are shown as having a square shape, in other embodiments, circuit
boards 108 have circular or other shapes.
[0022] Circuit boards 108 are composed of a substrate to
mechanically support and electrically couple electronic components
on circuit boards 108. As known to those skilled in the art,
circuit boards 108 are rigid structures that are typically composed
of silicon. Here, along with supporting electrical components,
circuit boards 108 are used to structurally support the electronic
components within frame 106.
[0023] Isolators 104 are located between circuit board assembly 102
and frame 106. Specifically, isolators 104 are located between
edges 112 of circuit board 108 and an inner surface 304 of frame
1-6. Isolators 104 are held in place between circuit board assembly
102 and frame 106 by equal and opposite force placed on isolators
104 by circuit board assembly 102 and frame 106 respectively. In
other words, circuit board assembly 102 places a force on isolators
104 in a first direction and frame 106 places a force on isolators
104 equal to the force of circuit board assembly and in a direction
opposite the first direction. These contradicting forces cancel out
to suspend isolators 104 in place between circuit board assembly
102 and frame 106. Additionally, return forces from isolators 104
on circuit board assembly 102, suspend circuit board assembly 102
within frame 106. In the embodiment shown in FIG. 2, isolators 104
are held in compression, such that circuit board assembly 102
places inward force (relative to the isolator 104) on isolator 104
and frame 106 also places inward force on the isolator 104. In an
alternative embodiment, isolators 104 are held in tension, such
that circuit board assembly 102 places outward force (relative to
isolator 104) on isolator 104 and frame 106 also places outward
force on isolator 104. The equal and opposite force holding
isolators 104 in place is explained in more detail with respect to
FIGS. 3-5 below.
[0024] Isolators 104 are located on edges 112 of circuit boards 108
such that the combined forces of isolators 104 hold circuit board
assembly 102 in place. In other words, the forces placed by each
isolator 104 on circuit board assembly 102 cancel each other out
such that circuit board assembly 102 is held in place within frame
102. This is explained in more detail with respect to FIGS. 3-5.
Forces are applied to isolators 104 by the rigid structure of frame
106 and the rigid structure of circuit board assembly 102.
[0025] Isolators 104 are composed of an elastomer material. In one
embodiment, isolators 104 consist essentially of an elastomer
material such that no metals or other materials are adhered or
molded to isolators 104 to enable coupling between isolators 104
and frame 106, and isolators 104 and circuit board assembly
102.
[0026] FIG. 3A is a top cross-sectional view of one embodiment of
electronic device 100. As shown isolator 104-1 is located on one
edge 112 of circuit boards 108 and isolator 104-3 is located on an
opposite edge 112 of circuit boards 108. Positioning isolators
104-1, 104-3 on opposite edges 112 of circuit boards 108 enables
equal and opposite forces to be placed on circuit board assembly
102 and on isolator 104-1 and isolator 104-3. This causes a
friction fit of circuit board assembly 102 within frame 106 which
holds circuit board assembly 102 and isolators 104-1 and 104-3 in
place.
[0027] In the embodiment shown in FIG. 3A, isolators 104-1, 104-3
are under compression while installed in frame 106. In equilibrium
isolators 104-1, 104-3 are slightly larger than the space they fill
between circuit board assembly 102 and frame 106. This increased
size places isolators 104-1, 104-3 in compression when installed in
frame 106. The compression causes isolators 104-1, 104-3 to be held
in place between frame 106 and circuit board assembly 102 by equal
and opposite forces. For example, the rigid structure of frame 106
places inward force on isolators 104-1, 104-3, while circuit board
assembly 102 places outward forces on isolators 104-1, 104-3.
[0028] As shown in FIG. 3A, isolator 104-2 is located on the bottom
of circuit board assembly 102 and a matching isolator 104-4 (not
shown in FIG. 3A) is on the opposite side (top) of circuit board
assembly 102. Similar to isolators 104-1, 104-3, isolators 104-2,
104-4 are held in place by equal and opposite forces.
[0029] In one embodiment, to install isolators 104 and circuit
board assembly 102 in frame 106, isolators are compressed prior to
installation. Here, isolators 104 are first installed on circuit
board assembly 102. While on circuit board assembly 102 isolators
104 are compressed, and circuit board assembly 102 with isolators
104 thereon is placed in frame 106. Isolators 104 are then allowed
to expand to contact and place force on frame 106. Circuit board
assembly 102 is thus held in place within frame 106 by the friction
caused by contact force between circuit board assembly 102 and
isolators 104 and friction caused by contact force between
isolators 104 and frame 106. Frame 106, therefore supports circuit
board assembly 102 via the friction between frame 106 and isolators
104 and the friction between isolators 104 and circuit boards 108
of circuit board assembly 102.
[0030] In another embodiment, body 110 of frame 106 comprises two
halves that are attached together to form body 110. Here, isolators
104 are installed on circuit board assembly 102 and the two halves
of body 110 are placed around circuit board assembly 102 and
isolators 104. The two halves of body 110 are then attached
together to form body 110. Cover 111 is then placed on body 110 to
complete frame 106.
[0031] In one embodiment an adhesive is placed between isolators
104 and circuit board assembly 102. The adhesive aids in holding
isolators 104 in place during installation of circuit board
assembly 102 and isolators 104 in frame 106. In another embodiment,
an adhesive is placed between isolators 104 and frame 106 to aid
the friction in holding isolators 104 to circuit board assembly
102.
[0032] FIG. 3B is a close up view of isolator 104-3 on circuit
board assembly 102 and installed in frame 106. As shown, isolator
104-3 is in compression and is held in place by equal and opposite
forces from circuit board assembly 102 and frame 106. The rigid
structure of circuit board assembly 102 places force on isolator
104-3 in the direction of arrow 306. Similarly, the rigid structure
of frame 106 places an equal force on isolator 104-3 in the
direction of arrow 308. The two forces compress isolator 104-3. The
compression of isolator 104-3 causes isolator 104-3 to exert return
forces against both circuit board assembly 102 and frame 106. The
force on the contact surfaces between isolator 104-3 and circuit
board assembly 102, and isolator 104-3 and frame 106, causes
friction which holds isolator 104-3 in place.
[0033] Additionally, since circuit board assembly 102 is placed
between isolators 104-1 and 104-3, the equal and opposite forces
and friction caused by isolators 104-1 and 104-3 and frame 106 hold
circuit board assembly 102 in place within frame 106.
[0034] Isolator 104-3 is shaped to generally match the contour of
inside surface 304 of frame 106. Isolator 104-3 is also shaped to
accept circuit board assembly 102. Thus, in one embodiment,
isolator 104-3 defines two grooves 302, one for each circuit board
108 of circuit board assembly 102. Each of grooves 302 is slightly
smaller than the width of the circuit board 108 when isolator 104
is in equilibrium. This enables isolator 104 to place force on
circuit board 108 when installed thereon.
[0035] In an alternative embodiment, isolator 104-3 does not have
grooves for circuit boards 108 and is not contoured to the internal
shape of frame 106. Instead, isolator 104-3 has a generally
rectangular shape in equilibrium and is forced into a general shape
such as shown in FIG. 3B by compression and pressure between
circuit board assembly 102 and frame 106.
[0036] In one embodiment, the edges of isolators 104 that contact
frame 106 and circuit board assembly 102 are drawn smooth. Smooth
edges increase the amount of area of surface to surface contact
between isolators 104, and circuit board assembly 102 and frame 106
respectively. The increased contact surface area increases the
amount of friction and thus holds circuit board assembly 102 more
securely in place.
[0037] In one embodiment, frame 106 comprises a plurality of
features on inner surface 304 of frame 106 to aid isolators 104 in
"grabbing" frame 106. In one embodiment, the plurality of features
are depressions in inner surface 304, such as, for example, grooves
or dimples. In another embodiment, the plurality of features are
projections from inner surface 304, such as, for example, spikes or
ridges. These features aid in securing circuit board assembly 102
from rotation and also aid isolators 104 in dampening rotational
vibration.
[0038] In one embodiment, isolators 104 are formed by cutting a
sheet of isolation material to the desired shape with, for example,
a laser. In other embodiments, the isolation sheet is cut with a
water jet, a die or other cutting techniques. In yet another
embodiment, isolators 104 are formed in a mold.
[0039] FIGS. 4A and 4B are cross-sectional views of electronic
device 100. FIG. 4A is a side cross-sectional view and FIG. 4B is a
perspective cross-sectional view. Each isolator 104-1, 104-2,
104-3, and 104-4 is located on one edge 112 of circuit boards 108
in circuit board assembly 102. Isolators 104-1, 104-2, 104-3, and
104-4 are located between circuit board assembly 102 and frame 106.
In this way isolators 104-1, 104-2, 104-3, and 104-4 cause equal
and opposite forces on circuit board assembly 102 which restrict
movement of circuit board assembly 102 in directions parallel to
the plane of circuit boards 108 in circuit board assembly 102.
Isolators 104-1, 104-2, 104-3, and 104-4 also restrict circuit
board assembly 102 from movement in directions perpendicular to the
plane of circuit boards 108. The circular cross section
(illustrated in FIG. 3A) of frame 106 aids in restricting movement
of circuit board assembly 102 in direction perpendicular to the
plane of circuit boards 108.
[0040] Isolator 104-1 is located on a first edge 112 of circuit
board assembly 102 and isolator 104-3 is located on a second edge
112 of circuit board assembly 102 opposite of isolator 104-1.
Isolator 104-1 and 104-3 form an imaginary line across circuit
board assembly 102, referred to herein as horizontal axis 402.
Isolator 104-3 is located directly opposite of isolator 104-1 on
circuit board assembly 102 which when combined with the rigid
structure of circuit board assembly 102 places pressure on frame
106. Similarly, isolator 104-2 is on one side of circuit board
assembly 102 and isolator 104-4 is on another side of circuit board
assembly 102 opposite of isolator 104-2. Isolator 104-4 and 104-2
form an imaginary axis through circuit board assembly 102, referred
to herein as vertical axis 404.
[0041] Isolators 104-1, 104-2, 104-3, and 104-4 are positioned such
that horizontal axis 402 and vertical axis 404 cross approximately
at the center of mass of circuit board assembly 102. The point at
which horizontal axis 402 and vertical axis 404 cross is referred
to herein as the center of isolation. Crossing at the center of
mass of circuit board assembly 102 aids in reducing frequencies
translated through isolators 104-1, 104-2, 104-3, and 104-4 to
circuit board assembly 102. In this embodiment, the center of mass
of circuit board assembly 102 is in the physical center of circuit
board assembly 102. Thus, horizontal axis 402 and vertical axis 404
cross at the center of circuit board assembly 102, and isolators
104-1, 104-2, 104-3, and 104-4 are centered on each edge of circuit
boards 108.
[0042] Isolators 104-1, 104-2, 104-3, and 104-4 isolate circuit
board assembly 102 from vibration coupled to frame 106 from
external sources by dampening the vibration. Isolators 104-1 and
104-3 primarily dampen incoming vibration in a vector parallel to
horizontal axis 402. Similarly, isolators 104-2 and 104-4 primarily
dampen incoming vibration in a vector parallel to vertical axis
404. Additionally, since each isolator 104-1, 104-2, 104-3, and
104-4 is friction fit between frame 106 and circuit board assembly
102, each isolator 104-1, 104-2, 104-3, and 104-4 also dampens
vibration in an axis normal to the plane of circuit boards. Thus,
isolators 104-1, 104-2, 104-3, and 104-4 provide 3 axes of
isolation to circuit board assembly 102. As mentioned above, since
isolators 104 provide isolation against rotational vibration as
well as linear vibration isolators 104 provide 3 axes of rotation
and linear isolation. Although in this embodiment, 3 axes of
isolation are provided for both rotation and linear isolation, in
other embodiments, either rotational or linear isolation may not
provided or isolation may not be provided on all 3 axes.
[0043] Isolators 104-1, 104-2, 104-3, and 104-4 each exhibit a
natural vibration frequency. At or near (just above or just below)
the natural frequency, isolators 104-1, 104-2, 104-3, and 104-4
amplify vibration energy. For frequencies farther below the natural
frequency, isolators 104-1, 104-2, 104-3, and 104-4 have minimal
affect, providing little or no dampening and causing no
amplification. For frequencies farther above the natural frequency,
isolators 104-1, 104-2, 104-3, and 104-4 attenuate (dampen) the
vibration energy.
[0044] The natural frequency for isolators 104-1, 104-2, 104-3, and
104-4 can be controlled based on the type of material isolators
104-1, 104-2, 104-3, and 104-4 are composed of, the amount of
compression in which isolators 104-1, 104-2, 104-3, and 104-4 are
placed under, and the amount of contact area between isolators
104-1, 104-2, 104-3, and 104-4 and frame 106. The stiffer the
material used for isolators 104-1, 104-2, 104-3, and 104-4, the
higher the natural frequency. Likewise, the more compression
isolators 104-1, 104-2, 104-3, and 104-4 are put under the higher
the natural frequency. Finally, the larger the contact area between
isolators 104-1, 104-2, 104-3, and 104-4 and frame 106, the higher
the natural frequency. Isolators 104-1, 104-2, 104-3, and 104-4,
therefore, are configured in terms of size, compression, and
contact area to achieve the desired dampening for a particular
application.
[0045] In one embodiment, isolators 104-1, 104-2, 104-3, and 104-4
are configured to set their natural frequency at or below the
environmental frequencies in which isolators 104-1, 104-2, 104-3,
and 104-4 are to dampen. The mass of the device to be isolated
(e.g. circuit board assembly 102) is also factored in to determine
the natural frequency of isolators 104-1, 104-2, 104-3, and 104-4.
For example, in one embodiment, electronic device 100 is in an
environment that produces vibration frequency at 450 Hz and higher.
Here, isolators 104-1, 104-2, 104-3, and 104-4, given the mass of
circuit board assembly 102, have their natural frequency set to 350
Hz in order to attenuate frequencies of 450 Hz and above.
[0046] As mentioned above, to control the natural frequency of
isolators 104-1, 104-2, 104-3, and 104-4, the material,
compression, and contact area are selected to meet the desired
dampening criteria. For example, in one embodiment, isolators
104-1, 104-2, 104-3, and 104-4 are composed of an elastomer
material having a durometer reading of 20. In addition to selection
of material for a base durometer reading, material can be selected
based on the performance of the material across a range of
temperatures. Thus, for example, in one embodiment, the temperature
range in which isolation is desired is -45.degree. C. to 85.degree.
C., and the material for isolator 104 is selected to such that the
durometer reading varies only slightly over the desired temperature
range. For example, in one embodiment isolators 104-1, 104-2,
104-3, and 104-4 are composed of 209E made by Barry Controls
International.
[0047] Additionally, in one embodiment, isolators 104-1, 104-2,
104-3, and 104-4 are placed under compression in the range of
5-25%. To select the compression of each isolator 104-1, 104-2,
104-3, and 104-4, the size of each isolator 104-1, 104-2, 104-3,
and 104-4 is selected prior to installation. The larger the size of
isolator 104-1, 104-2, 104-3, and 104-4 in equilibrium compared to
the installed size, the more compression the isolator 104-1, 104-2,
104-3, and 104-4 is under when installed. Finally, the size of
isolators 104-1, 104-2, 104-3, and 104-4 is also selected to
achieve the desired surface area of contact between isolators
104-1, 104-2, 104-3, and 104-4 and frame 106 as well as isolators
104-1, 104-2, 104-3, and 104-4 and circuit board assembly 102.
[0048] Although isolators 104 are shown and/or described as having
a specific shape and size, in other embodiments, isolators 104 have
other shapes and sizes of isolators 104 as desired for a particular
implementation. For example, in an alternative embodiment,
isolators 104 extend along each side and connect at corners of
circuit board assembly 102 forming a ring around circuit board
assembly. The ring is then compressed when installed in frame 106.
Since the ring extends along all four sides of circuit boards 108
in circuit board assembly 102, the ring provides isolation to
circuit board assembly 102 on 3-axes. Furthermore, although
electronic device 100 is shown and described as having four
isolators 104, other numbers of isolators may be used to achieve
3-axis isolation. For example, as mentioned above in one embodiment
a single isolator 104 extends around all sides of circuit board
assembly 102. In another embodiment, circuit boards 108 are
triangular in shape and three isolators 104 are used, one isolator
104 on each side of circuit boards 108.
[0049] FIG. 5 illustrates an exploded view of another embodiment of
an electronic device 500 including a means of isolating electronic
components from vibration. Electronic device 500 comprises a
circuit board assembly 502, a plurality of isolators 504, and a
frame 506. For explanation purposes, isolators 504 are labeled
individually as isolator 504-1, 504-2, 504-3, and 504-4, 504-5, and
504-6, and are referred to generally as "isolators 504".
[0050] Electronic device 500 isolates circuit board assembly 502
from external environmental vibration by dampening the external
vibration with isolators 504. Circuit board assembly 502 comprises
a plurality of circuit boards 508, each circuit board having four
edges 512 and two faces 514. Circuit board assembly 502 is
generally similar to circuit board assembly 102, except that each
circuit board 508 comprises a plurality of hooks 516. Hooks 516
enable connection of isolators 504-2, 504-4, 504-5, and 504-6 to
circuit boards 508. In one embodiment, hooks 516 are machined
portions of circuit boards 508.
[0051] Frame 506 is similar to frame 106 comprising a body 510 and
a cover 511. Frame 506 is a hollow cylinder with a top and a bottom
which houses circuit board assembly 502. Thus, in this embodiment,
frame 506 surrounds circuit board assembly 502 in all three
dimensions. Frame 506 is composed of a rigid material sufficient to
support circuit board assembly 502 and isolators 504. Frame 506
also enables rigid connection between frame 506 and another
structure (not shown). In one embodiment, frame 506 is composed of
aluminum, however; in other embodiments, frame 506 is composed of
other rigid materials such as steel or plastic.
[0052] Although as shown in FIG. 5, frame 506 surrounds circuit
board assembly 502 in three dimensions, in other embodiments, frame
506 is a ring, square, or other similar structure that encircles
circuit board assembly 502 along two axes and is open along a third
axis. Here, frame 506 still supports circuit board assembly 502 at
the locations of isolators 504. Furthermore, in yet another
embodiment, frame 506 substantially surrounds circuit board
assembly 502 in three dimensions, except for an aperture in frame
506 for connection of an electronic cable or the like to circuit
board assembly 506. Although in this embodiment, frame 506 is
cylindrical in shape, in other embodiments other shapes are used
including cube, rectilinear, and other simple or complex
shapes.
[0053] In this embodiment, isolators 504-1, 504-3 extend around
circuit boards 508 individually and couple to frame 106 on either
side of circuit boards 508. Isolators 504-2, 504-4, 504-5, and
504-6 coupled between hooks 516 on circuit boards 508 and frame
106. Similar to isolators 104, isolators 504 are held in place by
equal and opposite forces; however, isolators 504 are held in
tension. Similarly, circuit board assembly 502 is held in place
within frame 506 by equal and opposite forces placed on circuit
board assembly 502 by isolators 504 from frame 506.
[0054] FIG. 6 illustrates a side cross-sectional view of electronic
device 500 with circuit board assembly 502 installed in frame 506.
Isolators 504 are composed of an elastomer material. In one
embodiment, isolators 504 consist essentially of an elastomer
material such that no metals or other materials are used to provide
structure to isolators 504 or to attach isolators 504 to frame 506.
As shown, isolators 504-2, 504-5 are located on one edge 512 of
circuit boards 508 and isolators 504-4, 504-6 are located on an
opposite edge 512 of circuit boards 508. Positioning isolators
504-2, 504-5 on opposite edges 112 of circuit boards 508 relative
to isolators 504-4, 504-6 enables equal and opposite forces to be
placed on circuit board assembly 502 and on isolators 504-2, 504-4,
504-5, and 504-6.
[0055] Isolators 504 are held in tension between circuit board
assembly 502 and frame 506 or between opposing sides of frame 506.
Isolators 504-2, 504-4, 504-5, 504-6 are located between circuit
board assembly 502 and frame 506. Isolators 504-2, 504-4, 504-5,
504-6 are coupled to circuit board assembly 502 with hooks 516.
Hooks 516 are placed in apertures 602 defined in isolators 504-2,
504-4, 504-5, 504-6. Similarly, isolators 504-2, 504-4, 504-5,
504-6 are coupled to frame 106 with hooks 604. Hooks 604 are placed
in apertures 602 defined in isolators 504-2, 504-4, 504-5, 504-6.
To place isolators 504-2, 504-4, 504-5, 504-6 in tension, isolators
are slightly smaller in equilibrium, than the space the fill when
installed within electronic device 500. The decreased size places
isolators 504-2, 504-4, 504-5, 504-6 in compression when installed.
The tension causes isolators 504-2, 504-4, 504-5, 504-6 to be held
in place by equal and opposite forces. For example, the rigid
structure of frame 506 places outward force on isolators 504-2,
504-4, 504-5, 504-6, while circuit board assembly 502 places inward
forces on isolators 504-2, 504-4, 504-5, 504-6.
[0056] Additionally, isolators 504-1, 504-3 coupled to hooks 604 on
opposite sides of frame 506. Isolators 504-1, 504-3 extend around
circuit boards 508 and coupled to hooks 604 on frame 506. Thus,
isolators 504-1, 504-3 are stretched into tension between hooks 604
on frame 506. Isolators 504-1, 504-3 also hold circuit boards 508
in place via an aperture 606 that compresses against circuit boards
508. Aperture 606 is slightly smaller than the size of circuit
boards 508 such that isolators 504-1, 504-3 hold circuit boards 508
when installed thereon.
[0057] In one embodiment, to install isolators 504 and circuit
board assembly 502 in frame 506, isolators 504-1, 504-3 are
installed on circuit boards 508 as shown in FIG. 5. Circuit board
assembly 502 with isolators 504-1, 504-3 thereon is placed in frame
506. Isolators 504-1, 504-3 are then stretched such that apertures
602 couple with hooks 604 on frame 506. Likewise, isolators 504-2,
504-4, 504-5, 504-6 are stretched to couple apertures 602 with
hooks 604 on frame and hooks 516 on circuit boards 508. In another
embodiment, frame 506 comprises two halves that are attached
together to form frame 506.
[0058] In one embodiment, and adhesive is placed between apertures
606 in isolators 504 and circuit boards 508 to aid in holding
circuit boards 508 in place within isolators 504. Additionally, in
another embodiment, an adhesive is placed between apertures 602 and
hooks 516, and hooks 604 respectively to aid in holding isolators
504 to hooks 516 and hooks 604.
[0059] FIG. 7 is a cross-sectional view of one embodiment of
electronic device 500. As shown, isolators 504-4, 504-6 are in
tension and are held in place by equal and opposite forces from
circuit board assembly 502 and frame 506. The rigid structure of
circuit board assembly 502 places force on isolators 504-4, 504-6
in the direction of arrow 702. Likewise, the rigid structure of
frame 506 places an equal force on isolators 504-4, 504-6 in the
direction of arrow 704. The two forces place isolators 504-4, 504-6
in tension. Additionally, circuit board assembly 502 is held in
place by equal and opposite forces caused by isolators 504. In
particular, the tension of isolators 504-4, 504-6 causes isolators
to exert return forces against both circuit board assembly 102 and
frame 106. The forces of isolators 504-4, 504-6 and the forces of
isolators 504-2, 504-5 cancel each other out to hold circuit board
assembly 502 in place within frame 506.
[0060] In one embodiment, similar to isolators 104, the location of
isolators 504 around circuit board assembly 502 is selected to
place the center of isolation of isolators 504 near the center of
mass of circuit board assembly 502.
[0061] Isolators 504, therefore, provide 3 axes of isolation to
circuit board assembly 102. Isolators 504 provide isolation against
rotational vibration as well as linear vibration isolators 104, and
thus provide 3 axes of rotation and linear isolation. Although in
this embodiment, 3 axes of isolation are provided for both rotation
and linear isolation, in other embodiments, either rotational or
linear isolation may not provided or isolation may not be provided
on all 3 axes.
[0062] Isolators 504 each exhibit a natural vibration frequency. At
or near (just above or just below) the natural frequency, isolators
504 amplify vibration energy. For frequencies farther below the
natural frequency, isolators 504 have minimal affect, providing
little or no dampening and causing no amplification. For
frequencies farther above the natural frequency, isolators 504
attenuate (dampen) the vibration energy.
[0063] The natural frequency for isolators 504 can be controlled
based on the type of material isolators 504 are composed of, the
amount of tension in which isolators 504 are placed under. The
stiffer the material used for isolators 504, the higher the natural
frequency. Likewise, the more tension isolators 504 are put under
the higher the natural frequency. Finally, the amount of contact
area between isolators 504 and frame 506 affects the natural
frequency. Isolators 504, therefore, are configured in terms of
size, tension, and contact area to achieve the desired dampening
for a particular application.
[0064] In one embodiment, isolators 504 are configured to set their
natural frequency at or below the environmental frequencies in
which isolators 504 are to dampen. The mass of the device to be
isolated (e.g. circuit board assembly 502) is also factored in to
determine the natural frequency of isolators 504. For example, in
one embodiment, electronic device 500 is in an environment that
produces vibration frequency at 450 Hz and higher. Here, isolators
504, given the mass of circuit board assembly 502, have their
natural frequency set to 350 Hz in order to attenuate frequencies
of 450 Hz and above.
[0065] As mentioned above, to control the natural frequency of
isolators 504, the material, tension, and contact area are selected
to meet the desired dampening criteria. For example, in one
embodiment, isolators 504 are composed of an elastomer material
having a durometer reading of 20. In addition to selection of
material for a base durometer reading, material can be selected
based on the performance of the material across a range of
temperatures. Thus, for example, in one embodiment, the temperature
range in which isolation is desired is -45.degree. C. to 85.degree.
C., and the material for isolators 504 is selected to such that the
durometer reading varies only slightly over the desired temperature
range. For example, in one embodiment isolators 504 are composed of
209E made by Barry Controls International.
[0066] Additionally, in one embodiment, isolators 504 are placed
under tension in the range of 5-25%. To select the tension of each
isolator 504, the size of each isolator 504 is selected prior to
installation. The smaller the size of isolator 504 in equilibrium
compared to the installed size, the more tension the isolator 504
is under when installed. Finally, the size of isolators 504 is also
selected to achieve the desired area of contact between isolators
504 and frame 506 as well as isolators 504 and circuit board
assembly 502.
[0067] Although isolators 504 are shown and/or described as having
a specific shape and size, in other embodiments, isolators 504 have
other shapes and sizes of isolators 504 as desired for a particular
implementation. For example, in an alternative embodiment,
isolators 504 extend along each side and connect at corners of
circuit board assembly 504 forming a ring around circuit board
assembly. The ring is then placed in tension by coupling to hooks
when installed in frame 506. Since the ring extends along all four
sides of circuit boards 508 in circuit board assembly 502, the ring
provides isolation to circuit board assembly 502 on 3-axes.
Furthermore, although electronic device 500 is shown and described
as having six isolators 504, other numbers of isolators may be used
to achieve 3-axis isolation. For example, as mentioned above in one
embodiment a single isolator 504 extends around all sides of
circuit board assembly 502. In another embodiment, circuit boards
508 are triangular in shape and three isolators 504 are used, one
isolator 504 on each side of circuit boards 508.
[0068] Although the embodiments described above with reference to
FIG. 1 and FIG. 5 respectively discuss either compression or
tension isolators, in an alternative embodiment a combination of
compression and tension isolators are used in a single embodiment.
In other words, one or more isolators for isolating an electronic
device are in compression and one or more other isolators for
isolating the electronic device are in tension.
[0069] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that any arrangement, which is calculated to achieve the
same purpose, may be substituted for the specific embodiment shown.
This disclosure is intended to cover any adaptations or variations
of the inventions herein. Therefore, it is manifestly intended that
the inventions herein be limited only by the claims and the
equivalents thereof.
* * * * *